1
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Asaba T, Ivanov V, Thomas SM, Savrasov SY, Thompson JD, Bauer ED, Ronning F. Colossal anomalous Nernst effect in a correlated noncentrosymmetric kagome ferromagnet. Sci Adv 2021; 7:7/13/eabf1467. [PMID: 33771869 PMCID: PMC7997519 DOI: 10.1126/sciadv.abf1467] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 02/09/2021] [Indexed: 05/12/2023]
Abstract
The transverse voltage generated by a temperature gradient in a perpendicularly applied magnetic field, termed the Nernst effect, has promise for thermoelectric applications and for probing electronic structure. In magnetic materials, an anomalous Nernst effect (ANE) is possible in a zero magnetic field. We report a colossal ANE in the ferromagnetic metal UCo0.8Ru0.2Al, reaching 23 microvolts per kelvin. Uranium's 5f electrons provide strong electronic correlations that lead to narrow bands, a known route to producing a large thermoelectric response. In addition, uranium's strong spin-orbit coupling produces an intrinsic transverse response in this material due to the Berry curvature associated with the relativistic electronic structure. Theoretical calculations show that in UCo0.8Ru0.2Al at least 148 Weyl nodes, and two nodal lines, exist within 60 millielectron volt of the Fermi level. This work demonstrates that magnetic actinide materials can host strong Nernst and Hall responses due to their combined correlated and topological nature.
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Affiliation(s)
- T Asaba
- Materials Physics and Applications Division, Los Alamos National Laboratory, NM, 87545 USA.
| | - V Ivanov
- Department of Physics, University of California, Davis, CA 95616, USA
| | - S M Thomas
- Materials Physics and Applications Division, Los Alamos National Laboratory, NM, 87545 USA
| | - S Y Savrasov
- Department of Physics, University of California, Davis, CA 95616, USA
| | - J D Thompson
- Materials Physics and Applications Division, Los Alamos National Laboratory, NM, 87545 USA
| | - E D Bauer
- Materials Physics and Applications Division, Los Alamos National Laboratory, NM, 87545 USA
| | - F Ronning
- Institute for Materials Science, Los Alamos National Laboratory, NM, 87545 USA.
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2
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Thomas SM, Santos FB, Christensen MH, Asaba T, Ronning F, Thompson JD, Bauer ED, Fernandes RM, Fabbris G, Rosa PFS. Evidence for a pressure-induced antiferromagnetic quantum critical point in intermediate-valence UTe 2. Sci Adv 2020; 6:eabc8709. [PMID: 33055167 PMCID: PMC7556831 DOI: 10.1126/sciadv.abc8709] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/27/2020] [Indexed: 06/01/2023]
Abstract
UTe2 is a recently discovered unconventional superconductor that has attracted much interest because of its potentially spin-triplet topological superconductivity. Our ac calorimetry, electrical resistivity, and x-ray absorption study of UTe2 under applied pressure reveals key insights on the superconducting and magnetic states surrounding pressure-induced quantum criticality at P c1 = 1.3 GPa. First, our specific heat data at low pressures, combined with a phenomenological model, show that pressure alters the balance between two closely competing superconducting orders. Second, near 1.5 GPa, we detect two bulk transitions that trigger changes in the resistivity, which are consistent with antiferromagnetic order, rather than ferromagnetism. Third, the emergence of magnetism is accompanied by an increase in valence toward a U4+ (5f 2) state, which indicates that UTe2 exhibits intermediate valence at ambient pressure. Our results suggest that antiferromagnetic fluctuations may play a more substantial role on the superconducting state of UTe2 than previously thought.
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Affiliation(s)
- S M Thomas
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - F B Santos
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Escola de Engenharia de Lorena, Universidade de Sao Paulo (EEL-USP), Materials Engineering Department (Demar), Lorena, Sao Paolo, Brazil
| | - M H Christensen
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - T Asaba
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - R M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - P F S Rosa
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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3
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Bauer ED, Davis CW, Patroneva A, Dayno JM, Thorpy MJ. 0766 Safety And Tolerability Of Pitolisant In The Treatment Of Adult Patients With Narcolepsy: Final Analysis Of An Open-label, Expanded Access Program In The United States. Sleep 2020. [DOI: 10.1093/sleep/zsaa056.762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Introduction
Pitolisant Expanded Access Clinical Evaluation (PEACE) provided adult patients with narcolepsy access to treatment with pitolisant while it was an investigational medication in the United States.
Methods
Pitolisant was titrated to 35.6 mg/day (or the highest tolerable dose) over a 3-week period. Dose adjustments were permitted at the discretion of the treating physician based on patient response. Treating physicians followed their standard of care and were required to report adverse events (AEs). Demographic and baseline information for all enrolled patients, and safety results available through October 30, 2019, are reported here (presentation will include final data from the PEACE program).
Results
In all, 623 patients (67.9% female; 84.6% white; mean age, 40.0 years; narcolepsy type 1, 51.5%) were treated with pitolisant in the PEACE program. Nearly all patients (98.4%) had been previously treated with other narcolepsy medications (88.1% with ≥2 narcolepsy medications). Overall, 35.2% of patients discontinued from the program; 16.7% due to an AE and 12.2% for lack of effect. At Month 1, 97.3% of patients remained in the study, 88.2% at Month 3, 76.5% at Month 6, 66.9% at Month 9, and 55.0% at Month 12. In all, 256 (41.1%) patients experienced ≥1 AE; majority (52.5%) of these AEs occurred early in treatment (by Week 3). The most commonly reported AEs were headache (9.8% of AEs), nausea (6.6%), anxiety (5.6%), and insomnia (4.7%).
Conclusion
In the PEACE program, patient characteristics were generally reflective of the US narcolepsy patient population. The safety and tolerability profile of pitolisant was similar to that seen in the clinical development program, with no new safety signals identified. The program ceased enrollment in August 2019 after the US approval of pitolisant for the treatment of excessive daytime sleepiness in adult patients with narcolepsy.
Support
Harmony Biosciences, LLC.
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Affiliation(s)
- E D Bauer
- Harmony Biosciences, LLC, Plymouth Meeting, PA
| | - C W Davis
- Harmony Biosciences, LLC, Plymouth Meeting, PA
| | - A Patroneva
- Harmony Biosciences, LLC, Plymouth Meeting, PA
| | - J M Dayno
- Harmony Biosciences, LLC, Plymouth Meeting, PA
| | - M J Thorpy
- Albert Einstein College of Medicine, Bronx, NY
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4
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Pustogow A, Luo Y, Chronister A, Su YS, Sokolov DA, Jerzembeck F, Mackenzie AP, Hicks CW, Kikugawa N, Raghu S, Bauer ED, Brown SE. Constraints on the superconducting order parameter in Sr 2RuO 4 from oxygen-17 nuclear magnetic resonance. Nature 2019; 574:72-75. [PMID: 31548658 DOI: 10.1038/s41586-019-1596-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 07/15/2019] [Indexed: 11/09/2022]
Abstract
Phases of matter are usually identified through spontaneous symmetry breaking, especially regarding unconventional superconductivity and the interactions from which it originates. In that context, the superconducting state of the quasi-two-dimensional and strongly correlated perovskite Sr2RuO4 is considered to be the only solid-state analogue to the superfluid 3He-A phase1,2, with an odd-parity order parameter that is unidirectional in spin space for all electron momenta and breaks time-reversal symmetry. This characterization was recently called into question by a search for an expected 'split' transition in a Sr2RuO4 crystal under in-plane uniaxial pressure, which failed to find any such evidence; instead, a dramatic rise and a peak in a single-transition temperature were observed3,4. Here we use nuclear magnetic resonance (NMR) spectroscopy of oxygen-17, which is directly sensitive to the order parameter via hyperfine coupling to the electronic spin degrees of freedom, to probe the nature of superconductivity in Sr2RuO4 and its evolution under strain. A reduction of the Knight shift is observed for all strain values and at temperatures below the critical temperature, consistent with a drop in spin polarization in the superconducting state. In unstrained samples, our results contradict a body of previous NMR work reporting no change in the Knight shift5 and the most prevalent theoretical interpretation of the order parameter as a chiral p-wave state. Sr2RuO4 is an extremely clean layered perovskite and its superconductivity emerges from a strongly correlated Fermi liquid, and our work imposes tight constraints on the order parameter symmetry of this archetypal system.
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Affiliation(s)
- A Pustogow
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, USA.
| | - Yongkang Luo
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, USA. .,Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, China.
| | - A Chronister
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, USA
| | - Y-S Su
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, USA
| | - D A Sokolov
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - F Jerzembeck
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - A P Mackenzie
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany.,School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - C W Hicks
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - N Kikugawa
- National Institute for Materials Science, Tsukuba, Japan
| | - S Raghu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - S E Brown
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, USA.
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5
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Rosa PFS, Thomas SM, Balakirev FF, Bauer ED, Fernandes RM, Thompson JD, Ronning F, Jaime M. Enhanced Hybridization Sets the Stage for Electronic Nematicity in CeRhIn_{5}. Phys Rev Lett 2019; 122:016402. [PMID: 31012717 DOI: 10.1103/physrevlett.122.016402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 09/26/2018] [Indexed: 06/09/2023]
Abstract
High magnetic fields induce a pronounced in-plane electronic anisotropy in the tetragonal antiferromagnetic metal CeRhIn_{5} at H^{*}≳30 T for fields ≃20° off the c axis. Here we investigate the response of the underlying crystal lattice in magnetic fields to 45 T via high-resolution dilatometry. At low fields, a finite magnetic field component in the tetragonal ab plane explicitly breaks the tetragonal (C_{4}) symmetry of the lattice revealing a finite nematic susceptibility. A modest a-axis expansion at H^{*} hence marks the crossover to a fluctuating nematic phase with large nematic susceptibility. Magnetostriction quantum oscillations confirm a Fermi surface change at H^{*} with the emergence of new orbits. By analyzing the field-induced change in the crystal-field ground state, we conclude that the in-plane Ce 4f hybridization is enhanced at H^{*}, in agreement with the in-plane lattice expansion. We argue that the nematic behavior observed in this prototypical heavy-fermion material is of electronic origin, and is driven by the hybridization between 4f and conduction electrons which carries the f-electron anisotropy to the Fermi surface.
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Affiliation(s)
- P F S Rosa
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S M Thomas
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - F F Balakirev
- National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M Jaime
- National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545, USA
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6
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Modic KA, Bachmann MD, Ramshaw BJ, Arnold F, Shirer KR, Estry A, Betts JB, Ghimire NJ, Bauer ED, Schmidt M, Baenitz M, Svanidze E, McDonald RD, Shekhter A, Moll PJW. Resonant torsion magnetometry in anisotropic quantum materials. Nat Commun 2018; 9:3975. [PMID: 30266902 PMCID: PMC6162279 DOI: 10.1038/s41467-018-06412-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 08/29/2018] [Indexed: 11/09/2022] Open
Abstract
Unusual behavior in quantum materials commonly arises from their effective low-dimensional physics, reflecting the underlying anisotropy in the spin and charge degrees of freedom. Here we introduce the magnetotropic coefficient k = ∂2F/∂θ2, the second derivative of the free energy F with respect to the magnetic field orientation θ in the crystal. We show that the magnetotropic coefficient can be quantitatively determined from a shift in the resonant frequency of a commercially available atomic force microscopy cantilever under magnetic field. This detection method enables part per 100 million sensitivity and the ability to measure magnetic anisotropy in nanogram-scale samples, as demonstrated on the Weyl semimetal NbP. Measurement of the magnetotropic coefficient in the spin-liquid candidate RuCl3 highlights its sensitivity to anisotropic phase transitions and allows a quantitative comparison to other thermodynamic coefficients via the Ehrenfest relations.
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Affiliation(s)
- K A Modic
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany.
| | - Maja D Bachmann
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | - B J Ramshaw
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, 14853, USA
| | - F Arnold
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | - K R Shirer
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | - Amelia Estry
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | - J B Betts
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Nirmal J Ghimire
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.,Argonne National Laboratory, Lemont, IL, 60439, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Marcus Schmidt
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | - Michael Baenitz
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | - E Svanidze
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany
| | | | - Arkady Shekhter
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Philip J W Moll
- Max-Planck-Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, D-01187, Dresden, Germany. .,EPFL STI IMX-GE MXC 240, CH-1015, Lausanne, Switzerland.
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7
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Stock C, Rodriguez-Rivera JA, Schmalzl K, Demmel F, Singh DK, Ronning F, Thompson JD, Bauer ED. From Ising Resonant Fluctuations to Static Uniaxial Order in Antiferromagnetic and Weakly Superconducting CeCo(In_{1-x}Hg_{x})_{5}(x=0.01). Phys Rev Lett 2018; 121:037003. [PMID: 30085774 DOI: 10.1103/physrevlett.121.037003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Indexed: 06/08/2023]
Abstract
CeCo(In_{0.990}Hg_{0.010})_{5} is a charge doped variant of the d-wave CoCoIn_{5} superconductor with coexistent antiferromagnetic and superconducting transitions occurring at T_{N}=3.4 and T_{c}=1.4 K, respectively. We use neutron diffraction and spectroscopy to show that the magnetic resonant fluctuations present in the parent superconducting phase are replaced by collinear c-axis magnetic order with three-dimensional Ising critical fluctuations. No low-energy transverse spin fluctuations are observable in this doping-induced antiferromagnetic phase and the dynamic resonant spectral weight predominately shifts to the elastic channel. Static (τ>0.2 ns) collinear Ising order is proximate to superconductivity in CeCoIn_{5} and is stabilized through hole doping with Hg.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - K Schmalzl
- Forschungszentrum Juelich GmbH, Juelich Centre for Neutron Science at ILL, 71 avenue des Martyrs, 38000 Grenoble, France
| | - F Demmel
- ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot OX11 0QX, United Kingdom
| | - D K Singh
- Department of Physics and Astronomy, University of Missouri, Missouri 65211, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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8
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Fobes DM, Bauer ED, Thompson JD, Sazonov A, Hutanu V, Zhang S, Ronning F, Janoschek M. Low temperature magnetic structure of CeRhIn 5 by neutron diffraction on absorption-optimized samples. J Phys Condens Matter 2017; 29:17LT01. [PMID: 28349895 DOI: 10.1088/1361-648x/aa6696] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two aspects of the ambient pressure magnetic structure of heavy fermion material CeRhIn5 have remained under some debate since its discovery: whether the structure is indeed an incommensurate helix or a spin density wave, and what is the precise magnitude of the ordered magnetic moment. By using a single crystal sample optimized for hot neutrons to minimize neutron absorption by Rh and In, here we report an ordered moment of [Formula: see text]. In addition, by using spherical neutron polarimetry measurements on a similar single crystal sample, we have confirmed the helical nature of the magnetic structure, and identified a single chiral domain.
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Affiliation(s)
- D M Fobes
- MPA-CMMS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States of America
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9
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Huang K, Eley S, Rosa PFS, Civale L, Bauer ED, Baumbach RE, Maple MB, Janoschek M. Quantum Critical Scaling in the Disordered Itinerant Ferromagnet UCo_{1-x}Fe_{x}Ge. Phys Rev Lett 2016; 117:237202. [PMID: 27982631 DOI: 10.1103/physrevlett.117.237202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Indexed: 06/06/2023]
Abstract
The Belitz-Kirkpatrick-Vojta (BKV) theory shows in excellent agreement with experiment that ferromagnetic quantum phase transitions (QPTs) in clean metals are generally first order due to the coupling of the magnetization to electronic soft modes, in contrast to the classical analogue that is an archetypical second-order phase transition. For disordered metals the BKV theory predicts that the second-order nature of the QPT is restored because the electronic soft modes change their nature from ballistic to diffusive. Our low-temperature magnetization study identifies the ferromagnetic QPT in the disordered metal UCo_{1-x}Fe_{x}Ge as the first clear example that exhibits the associated critical exponents predicted by the BKV theory.
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Affiliation(s)
- K Huang
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - S Eley
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P F S Rosa
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - L Civale
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R E Baumbach
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M B Maple
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - M Janoschek
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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10
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Abstract
We report the effect of hydrostatic pressure on the magnetotransport properties of the Weyl semimetal NbAs. Subtle changes can be seen in the ρ(xx)(T) profiles with pressure up to 2.31 GPa. The Fermi surfaces undergo an anisotropic evolution under pressure: the extremal areas slightly increase in the k(x)-k(y) plane, but decrease in the k(z)-k(y)(k(x)) plane. The topological features of the two pockets observed at atmospheric pressure, however, remain unchanged at 2.31 GPa. No superconductivity can be seen down to 0.3 K for all the pressures measured. By fitting the temperature dependence of specific heat to the Debye model, we obtain a small Sommerfeld coefficient γ(0) = 0.09(1) mJ (mol·K(2))(-1) and a large Debye temperature, Θ(D) = 450(9) K, confirming a 'hard' crystalline lattice that is stable under pressure. We also studied the Kadowaki-Woods ratio of this low-carrier-density massless system, R(KW) = 3.2 × 10(4) μΩ cm mol(2) K(2) J(-2). After accounting for the small carrier density in NbAs, this R(KW) indicates a suppressed transport scattering rate relative to other metals.
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Affiliation(s)
- Yongkang Luo
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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11
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Kang M, Wakeham N, Ni N, Bauer ED, Kim J, Ronning F. Thermal and transport properties of U2Pt(x)Ir(1-x)C2. J Phys Condens Matter 2015; 27:365702. [PMID: 26302330 DOI: 10.1088/0953-8984/27/36/365702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report thermal and transport properties of U2Pt x Ir1-x C2 from which a magnetic phase diagram is obtained. Pure U2IrC2 is an antiferromagnet at 6.5 K, whose Néel temperature initially rises to 13.2 K at x = 0.2 and subsequently is suppressed to zero temperature with increasing Pt content near x = 0.6. Heat capacity divided by temperature at x = 0.6 shows an upturn at low temperature, consistent with the expectations of enhanced quantum fluctuations in the presence of an underlying quantum critical point. The entropy after the phonon contribution has been subtracted has a value of 0.24 Rln2 at the Néel temperature of U2IrC2, revealing an itinerant nature of the 5 f electrons in this compound. On the Pt rich side of the phase diagram, superconductivity is suppressed by x = 0.85. The residual resistivity increases by a factor of 10 from pure Pt (x = 1) to x = 0.85 where superconductivity is suppressed to zero. By comparing the phase diagram of Ir doped U2PtC2 with the phase diagram of pressure tuned and Rh doped U2PtC2 we demonstrate the role of electronic tuning in this system.
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Affiliation(s)
- Mingu Kang
- CALDES, Institute of Basic Science, Pohang, Gyeongbuk 790-784, Korea. Department of Physics, Pohang University of Science and Technology (POSTECH) Pohang, Gyeongbuk 790-784, Korea. Los Alamos National Laboratory, Materials Physics and Applications Division, Los Alamos, NM 87545, USA
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12
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Ghimire NJ, Calder S, Janoschek M, Bauer ED. Magnetic structure of the antiferromagnetic Kondo lattice compounds CeRhAl₄Si₂ and CeIrAl₄Si₂. J Phys Condens Matter 2015; 27:245603. [PMID: 26030831 DOI: 10.1088/0953-8984/27/24/245603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have investigated the magnetic ground state of the antiferromagnetic Kondo-lattice compounds CeMAl4Si2(M = Rh, Ir) using neutron powder diffraction. Although both of these compounds show two magnetic transitions T(N1) and T(N2) in the bulk properties measurements, evidence for magnetic long-range order was only found below the lower transition T(N2). Analysis of the diffraction profiles reveals a commensurate antiferromagnetic structure with a propagation vector k = (0, 0, 1/2). The magnetic moment in the ordered state of CeRhAl4Si2 and CeIrAl4Si2 were determined to be 1.14(2) and 1.41(3) μ(B) Ce(-1), respectively, and are parallel to the crystallographic c-axis in agreement with magnetic susceptibility measurements.
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Affiliation(s)
- N J Ghimire
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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13
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Abstract
We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse and longitudinal magnetoresistance in the plane of this tetragonal structure does not saturate up to 9 T. In the transverse configuration (H ∥ c, I ⊥ c) it is 230,000% at 2 K. The Hall coefficient changes sign from hole-like at room temperature to electron-like below ∼150 K. The electron carrier density and mobility calculated at 2 K based on a single band approximation are 1.8 × 10(19) cm(-3) and 3.5 × 10(5) cm(2) Vs(-1), respectively. These values are similar to reported values for TaAs and NbP, and further emphasize that this class of noncentrosymmetric, transition-metal monopnictides is a promising family to explore the properties of Weyl semimetals and the consequences of their novel electronic structure.
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Affiliation(s)
- N J Ghimire
- Los Alamos National Lab, Los Alamos, NM 87544, USA
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14
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Chen Y, Jiang WB, Guo CY, Ronning F, Bauer ED, Park T, Yuan HQ, Fisk Z, Thompson JD, Lu X. Reemergent superconductivity and avoided quantum criticality in Cd-doped CeIrIn(5) under pressure. Phys Rev Lett 2015; 114:146403. [PMID: 25910144 DOI: 10.1103/physrevlett.114.146403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Indexed: 06/04/2023]
Abstract
We investigated the electrical resistivity and heat capacity of 1% Cd-doped CeIrIn_{5} under hydrostatic pressure up to 2.7 GPa, near where long-range antiferromagnetic order is suppressed and bulk superconductivity suddenly reemerges. The pressure-induced T_{c} is close to that of pristine CeIrIn_{5} at 2.7 GPa, and no signatures of a quantum critical point under pressure support a local origin of the antiferromagnetic moments in Cd-CeIrIn_{5} at ambient pressure. Similarities between superconductors CeIrIn_{5} and CeCoIn_{5} in response to Cd substitutions suggest a common magnetic mechanism.
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Affiliation(s)
- Y Chen
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - C Y Guo
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Tuson Park
- Department of Physics, Sungkyunkwan University, Suwon 440-746, South Korea
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Z Fisk
- Department of Physics, University of California, Irvine, California 92697, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Xin Lu
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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15
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Mounce AM, Yasuoka H, Koutroulakis G, Ni N, Bauer ED, Ronning F, Thompson JD. Detection of a spin-triplet superconducting phase in oriented polycrystalline U(2)PtC(2) samples using ^(195)Pt nuclear magnetic resonance. Phys Rev Lett 2015; 114:127001. [PMID: 25860768 DOI: 10.1103/physrevlett.114.127001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Indexed: 06/04/2023]
Abstract
Nuclear magnetic resonance (NMR) measurements on the ^{195}Pt nucleus in an aligned powder of the moderately heavy-fermion material U_{2}PtC_{2} are consistent with spin-triplet pairing in its superconducting state. Across the superconducting transition temperature and to much lower temperatures, the NMR Knight shift is temperature independent for field both parallel and perpendicular to the tetragonal c axis, expected for triplet equal-spin pairing superconductivity. The NMR spin-lattice relaxation rate 1/T_{1}, in the normal state, exhibits characteristics of ferromagnetic fluctuations, compatible with an enhanced Wilson ratio. In the superconducting state, 1/T_{1} follows a power law with temperature without a coherence peak giving additional support that U_{2}PtC_{2} is an unconventional superconductor. Bulk measurements of the ac susceptibility and resistivity indicate that the upper critical field exceeds the Pauli limiting field for spin-singlet pairing and is near the orbital limiting field, an additional indication for spin-triplet pairing.
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Affiliation(s)
- A M Mounce
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - H Yasuoka
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - G Koutroulakis
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - N Ni
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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16
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Kung HH, Baumbach RE, Bauer ED, Thorsmølle VK, Zhang WL, Haule K, Mydosh JA, Blumberg G. Chirality density wave of the “hidden order” phase in URu
2
Si
2. Science 2015; 347:1339-42. [DOI: 10.1126/science.1259729] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- H.-H. Kung
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - R. E. Baumbach
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - E. D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - V. K. Thorsmølle
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - W.-L. Zhang
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - K. Haule
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - J. A. Mydosh
- Kamerlingh Onnes Laboratory, Leiden University, 2300 RA Leiden, Netherlands
| | - G. Blumberg
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia
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17
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Ghimire NJ, Ronning F, Williams DJ, Scott BL, Luo Y, Thompson JD, Bauer ED. Investigation of the physical properties of the tetragonal CeMAl4Si2 (M = Rh, Ir, Pt) compounds. J Phys Condens Matter 2015; 27:025601. [PMID: 25501402 DOI: 10.1088/0953-8984/27/2/025601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The synthesis, crystal structure and physical properties studied by means of x-ray diffraction, magnetic, thermal and transport measurements of CeMAl4Si2 (M = Rh, Ir, Pt) are reported, along with the electronic structure calculations for LaMAl4Si2 (M = Rh, Ir, Pt). These materials adopt a tetragonal crystal structure (space group P4/mmm) comprised of BaAl4 blocks, separated by MAl2 units, stacked along the c-axis. Both CeRhAl4Si2 and CeIrAl4Si2 order antiferromagnetically below TN1 = 14 and 16 K, respectively, and undergo a second antiferromagnetic transitition at lower temperature (TN2 = 9 and 14 K, respectively). CePtAl4Si2 orders ferromagnetically below TC = 3 K with an ordered moment of μsat = 0.8 μB for a magnetic field applied perpendicular to the c-axis. Electronic structure calculations reveal quasi-2D character of the Fermi surface.
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Affiliation(s)
- N J Ghimire
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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18
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Wang CH, Poudel L, Taylor AE, Lawrence JM, Christianson AD, Chang S, Rodriguez-Rivera JA, Lynn JW, Podlesnyak AA, Ehlers G, Baumbach RE, Bauer ED, Gofryk K, Ronning F, McClellan KJ, Thompson JD. Quantum critical fluctuations in the heavy fermion compound Ce(Ni0.935Pd0.065)₂Ge₂. J Phys Condens Matter 2015; 27:015602. [PMID: 25469766 DOI: 10.1088/0953-8984/27/1/015602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Electric resistivity, specific heat, magnetic susceptibility, and inelastic neutron scattering experiments were performed on a single crystal of the heavy fermion compound Ce(Ni0.935Pd0.065)2Ge2 in order to study the spin fluctuations near an antiferromagnetic (AF) quantum critical point (QCP). The resistivity and the specific heat coefficient for T ⩽ 1 K exhibit the power law behavior expected for a 3D itinerant AF QCP (ρ(T) ∼ T(3/2) and γ(T) ∼ γ0 - bT(1/2)). However, for 2 ⩽ T ⩽ 10 K, the susceptibility and specific heat vary as log T and the resistivity varies linearly with temperature. Furthermore, despite the fact that the resistivity and specific heat exhibit the non-Fermi liquid behavior expected at a QCP, the correlation length, correlation time, and staggered susceptibility of the spin fluctuations remain finite at low temperature. We suggest that these deviations from the divergent behavior expected for a QCP may result from alloy disorder.
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Affiliation(s)
- C H Wang
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. University of California, Irvine, CA 92697, USA
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19
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Das P, Lin SZ, Ghimire NJ, Huang K, Ronning F, Bauer ED, Thompson JD, Batista CD, Ehlers G, Janoschek M. Magnitude of the magnetic exchange interaction in the heavy-fermion antiferromagnet CeRhIn₅. Phys Rev Lett 2014; 113:246403. [PMID: 25541784 DOI: 10.1103/physrevlett.113.246403] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Indexed: 06/04/2023]
Abstract
We have used high-resolution neutron spectroscopy experiments to determine the complete spin wave spectrum of the heavy-fermion antiferromagnet CeRhIn₅. The spin wave dispersion can be quantitatively reproduced with a simple frustrated J₁-J₂ model that also naturally explains the magnetic spin-spiral ground state of CeRhIn₅ and yields a dominant in-plane nearest-neighbor magnetic exchange constant J₀=0.74(3) meV. Our results pave the way to a quantitative understanding of the rich low-temperature phase diagram of the prominent CeTIn₅ (T=Co, Rh, Ir) class of heavy-fermion materials.
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Affiliation(s)
- Pinaki Das
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S-Z Lin
- T-4, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - N J Ghimire
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - K Huang
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - F Ronning
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C D Batista
- T-4, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - G Ehlers
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA
| | - M Janoschek
- Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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20
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Sakai H, Tokunaga Y, Kambe S, Urbano RR, Suzuki MT, Kuhns PL, Reyes AP, Tobash PH, Ronning F, Bauer ED, Thompson JD. Emergent antiferromagnetism out of the "hidden-order" state in URu2Si2: high magnetic field nuclear magnetic resonance to 40 T. Phys Rev Lett 2014; 112:236401. [PMID: 24972218 DOI: 10.1103/physrevlett.112.236401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Indexed: 06/03/2023]
Abstract
Very high field (29)Si-NMR measurements using a fully (29)Si-enriched URu(2)Si(2) single crystal were carried out in order to microscopically investigate the "hidden order" (HO) state and adjacent magnetic phases in the high field limit. At the lowest measured temperature of 0.4 K, a clear anomaly reflecting a Fermi surface instability near 22 T inside the HO state is detected by the (29)Si shift, (29)K(c). Moreover, a strong enhancement of (29)K(c) develops near a critical field H(c) ≃ 35.6 T, and the ^{29}Si-NMR signal disappears suddenly at H(c), indicating the total suppression of the HO state. Nevertheless, a weak and shifted (29)Si-NMR signal reappears for fields higher than H(c) at 4.2 K, providing evidence for a magnetic structure within the magnetic phase caused by the Ising-type anisotropy of the uranium ordered moments.
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Affiliation(s)
- H Sakai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Tokunaga
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - S Kambe
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - R R Urbano
- Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, 13083-859 Campinas, SP, Brazil and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - M-T Suzuki
- CCSE, Japan Atomic Energy Agency, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8587, Japan
| | - P L Kuhns
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - A P Reyes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - P H Tobash
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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21
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Fanelli VR, Lawrence JM, Goremychkin EA, Osborn R, Bauer ED, McClellan KJ, Thompson JD, Booth CH, Christianson AD, Riseborough PS. Q-dependence of the spin fluctuations in the intermediate valence compound CePd3. J Phys Condens Matter 2014; 26:225602. [PMID: 24824417 DOI: 10.1088/0953-8984/26/22/225602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report inelastic neutron scattering experiments on a single crystal of the intermediate valence compound CePd3. At 300 K the magnetic scattering is quasielastic, with half-width Γ = 23 meV, and is independent of momentum transfer Q. At low temperature, the Q-averaged magnetic spectrum is inelastic, exhibiting a broad peak centered near Emax = 55 meV. These results, together with the temperature dependence of the susceptibility, 4f occupation number, and specific heat, can be fit by the Kondo/Anderson impurity model. The low temperature scattering near Emax, however, shows significant variations with Q, reflecting the coherence of the 4f lattice. The intensity is maximal at (1/2, 1/2, 0), intermediate at (1/2, 0, 0) and (0, 0, 0), and weak at (1/2, 1/2, 1/2). We discuss this Q-dependence in terms of current ideas about coherence in heavy fermion systems.
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Affiliation(s)
- V R Fanelli
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA. Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
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22
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Treske U, Khoshkhoo MS, Roth F, Knupfer M, Bauer ED, Sarrao JL, Büchner B, Koitzsch A. X-ray photoemission study of CeTIn(5) (T = Co, Rh, Ir). J Phys Condens Matter 2014; 26:205601. [PMID: 24786193 DOI: 10.1088/0953-8984/26/20/205601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigated CeTIn5 (T = Co, Rh, Ir) using temperature- and angle-dependent x-ray photoemission spectroscopy. The Ce 3d core level has a very similar shape for all three materials and is indicative of weak f-hybridization. The spectra were analyzed using a simplified version of the Anderson impurity model, which yields a Ce 4f occupancy that is larger than 0.9. The temperature dependence shows a continuous, irreversible and exclusive broadening of the Ce 3d peaks, due to oxidation of Ce at the surface.
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Affiliation(s)
- U Treske
- Institute for Solid State Research, IFW-Dresden, PO Box 270116, DE-01171 Dresden, Germany
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23
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Chudo H, Koutroulakis G, Yasuoka H, Bauer ED, Tobash PH, Mitchell JN, Thompson JD. Weak itinerant antiferromagnetism in PuIn3 explored using 115In nuclear quadrupole resonance. J Phys Condens Matter 2014; 26:036001. [PMID: 24334529 DOI: 10.1088/0953-8984/26/3/036001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The results of (115)In nuclear quadrupole resonance (NQR) measurements on PuIn3 are reported. Three of the four NQR lines of (115)In expected for nuclear spin I = 9/2 are observed. The equal spacing of these lines at 20 K yields the NQR frequency of νQ = 10.45 MHz, and the asymmetry parameter of the electric field gradient η = 0. The NQR line profile and the nuclear spin-lattice relaxation rate 1/T1 display an abrupt change at 14 K, which is associated with the onset of long-range antiferromagnetic order. The temperature dependences of the staggered magnetization MQ(T), extracted from the NQR spectra, and 1/T1 below TN = 14 K are well explained by the self-consistent renormalization (SCR) theory for spin fluctuations. In addition, the scaling between T1T and MQ(T)/MQ(0) is also consistent with the predictions of SCR theory, providing further evidence that PuIn3 is a weak itinerant antiferromagnet in which spin fluctuations around the antiferromagnetic wavevector play a major role in the system's behavior at finite temperatures.
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Affiliation(s)
- H Chudo
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
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24
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Baumbach RE, Scott BL, Ronning F, Thompson JD, Bauer ED. Single crystal study of antiferromagnetic CePd3Al9. J Phys Condens Matter 2014; 26:025601. [PMID: 24326344 DOI: 10.1088/0953-8984/26/2/025601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Single crystal x-ray diffraction, magnetic susceptibility (M), heat capacity (C), and electrical resistivity (ρ) measurements are reported for specimens of the new tetragonal compound CePd3Al9, which forms in a new structure type. X-ray diffraction measurements reveal that the nearest neighbor Ce-Ce distances are large (d(Ce-Ce) = 5.272 Å), suggesting that this compound may be described as a stoichiometric dilute Kondo lattice. Thermodynamic and transport measurements reveal antiferromagnetic order near T(N) = 0.9 K. The ordered ground state emerges from a lattice of localized Ce ions that are weakly hybridized with the conduction electrons, as revealed by the moderate electronic coefficient of the specific heat γ ≈ 45 mJ mol(-1) K(-2) (extrapolated from above T(N)) and the lack of evidence for Kondo coherence in the magnetic susceptibility and electrical resistivity. The application of a magnetic field initially suppresses the magnetic order at a rate of -0.04 K kOe(-1), but Zeeman splitting of the doublet ground state produces a nonmagnetic singlet before TN reaches zero. The data additionally reveal that chemical/structural disorder plays an important role, as evidenced by results from single crystal x-ray diffraction, the broadness of the peak at TN in the heat capacity, and the small residual resistivity ratio RRR = ρ(300 K)/ρ0 = 1.3.
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Affiliation(s)
- R E Baumbach
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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25
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Abstract
Quantum criticality in the normal and superconducting states of the heavy-fermion metal CeCoIn5 is studied by measurements of the magnetic Grüneisen ratio ΓH and specific heat in different field orientations and temperatures down to 50 mK. A universal temperature over magnetic field scaling of ΓH in the normal state indicates a hidden quantum critical point at zero field. Within the superconducting state, the quasiparticle entropy at constant temperature increases upon reducing the field towards zero, providing additional evidence for zero-field quantum criticality.
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Affiliation(s)
- Y Tokiwa
- I. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P Gegenwart
- I. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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26
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Qi J, Durakiewicz T, Trugman SA, Zhu JX, Riseborough PS, Baumbach R, Bauer ED, Gofryk K, Meng JQ, Joyce JJ, Taylor AJ, Prasankumar RP. Measurement of two low-temperature energy gaps in the electronic structure of antiferromagnetic USb2 using ultrafast optical spectroscopy. Phys Rev Lett 2013; 111:057402. [PMID: 23952443 DOI: 10.1103/physrevlett.111.057402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 06/02/2023]
Abstract
Ultrafast optical spectroscopy is used to study the antiferromagnetic f-electron system USb(2). We observe the opening of two charge gaps at low temperatures (</~45 K), arising from renormalization of the electronic structure. Analysis of our data indicates that one gap is due to hybridization between localized f-electron and conduction electron bands, while band renormalization involving magnons leads to the emergence of the second gap. These experiments thus enable us to shed light on the complex electronic structure emerging at the Fermi surface in f-electron systems.
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Affiliation(s)
- J Qi
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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27
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Gofryk K, Ronning F, Zhu JX, Ou MN, Tobash PH, Stoyko SS, Lu X, Mar A, Park T, Bauer ED, Thompson JD, Fisk Z. Electronic tuning and uniform superconductivity in CeCoIn5. Phys Rev Lett 2012; 109:186402. [PMID: 23215302 DOI: 10.1103/physrevlett.109.186402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 09/11/2012] [Indexed: 06/01/2023]
Abstract
We report a globally reversible effect of electronic tuning on the magnetic phase diagram in CeCoIn(5) driven by electron (Pt and Sn) and hole (Cd, Hg) doping. Consequently, we are able to extract the superconducting pair breaking component for hole and electron dopants with pressure and codoping studies, respectively. We find that these nominally nonmagnetic dopants have a remarkably weak pair breaking effect for a d-wave superconductor. The pair breaking is weaker for hole dopants, which induce magnetic moments, than for electron dopants. Furthermore, both Pt and Sn doping have a similar effect on superconductivity despite being on different dopant sites, arguing against the notion that superconductivity lives predominantly in the CeIn(3) planes of these materials. In addition, we shed qualitative understanding on the doping dependence with density functional theory calculations.
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Affiliation(s)
- K Gofryk
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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28
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Tokiwa Y, Bauer ED, Gegenwart P. Quasiparticle entropy in the high-field superconducting phase of CeCoIn(5). Phys Rev Lett 2012; 109:116402. [PMID: 23005654 DOI: 10.1103/physrevlett.109.116402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 06/22/2012] [Indexed: 06/01/2023]
Abstract
The heavy-fermion superconductor CeCoIn(5) displays an additional transition within its superconducting (SC) state, whose nature is characterized by high-precision studies of the isothermal field dependence of the entropy, derived from combined specific heat and magnetocaloric effect measurements at temperatures T≥100 mK and fields H≤12 T aligned along different directions. For any of these conditions, we do not observe an additional entropy contribution upon tuning at constant temperature by magnetic field from the homogeneous SC into the presumed Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) SC state. By contrast, for H∥[100] a reduction of entropy was found that quantitatively agrees with the expectation for spin-density-wave order without FFLO superconductivity. Our data exclude the formation of a FFLO state in CeCoIn(5) for out-of-plane field directions, where no spin-density-wave order exists.
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Affiliation(s)
- Y Tokiwa
- I. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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29
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Baumbach RE, Lu X, Ronning F, Thompson JD, Bauer ED. Pressure tuned ferromagnetism in CeRu(2)M(2)X (M = Al, Ga; X = B, C). J Phys Condens Matter 2012; 24:325601-7. [PMID: 22809834 DOI: 10.1088/0953-8984/24/32/325601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The temperature (T)-pressure (P) phase diagrams are reported for the tetragonal layered compounds CeRu(2)Al(2)B, CeRu(2)Ga(2)B, and CeRu(2)Ga(2)C, studied by magnetization, specific heat and electrical resistivity. These systems exhibit localized 4f magnetic ordering with ferromagnetic ground states at T(C) = 12.8 K, 16.3 K, and 17.2 K, respectively. Chemical and applied pressure both increase T(C) in a similar manner. The evolution of properties with chemical and applied pressure suggests that these phase diagrams may be connected in a Doniach-like picture where CeRu(2)Al(2)B is furthest from the possible quantum phase transition and CeRu(2)Ga(2)C is the nearest.
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Affiliation(s)
- R E Baumbach
- MPA-CMMS Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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Park WK, Tobash PH, Ronning F, Bauer ED, Sarrao JL, Thompson JD, Greene LH. Observation of the hybridization gap and Fano resonance in the Kondo lattice URu2Si2. Phys Rev Lett 2012; 108:246403. [PMID: 23004299 DOI: 10.1103/physrevlett.108.246403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Indexed: 06/01/2023]
Abstract
The nature of the second-order phase transition that occurs in URu2Si2 at 17.5 K remains puzzling despite intensive research. A key question emerging in the field is whether a hybridization gap between the renormalized bands can be identified as the "hidden" order parameter. We report on the measurement of a hybridization gap in URu2Si2 employing a spectroscopic technique based on quasiparticle scattering. The differential conductance exhibits an asymmetric double-peak structure, a clear signature for a Fano resonance in a Kondo lattice. The hybridization gap opens well above 17.5 K, indicating that it is not the hidden order parameter. Our results put stringent constraints on the origin of the hidden order transition in URu2Si2 and demonstrate that quasiparticle scattering spectroscopy can probe the band renormalizations in a Kondo lattice via detection of a novel type of Fano resonance.
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Affiliation(s)
- W K Park
- Department of Physics and the Frederick Seitz Material Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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31
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Yasuoka H, Koutroulakis G, Chudo H, Richmond S, Veirs DK, Smith AI, Bauer ED, Thompson JD, Jarvinen GD, Clark DL. Observation of 239Pu nuclear magnetic resonance. Science 2012; 336:901-4. [PMID: 22605773 DOI: 10.1126/science.1220801] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In principle, the spin-½ plutonium-239 ((239)Pu) nucleus should be active in nuclear magnetic resonance spectroscopy. However, its signal has eluded detection for the past 50 years. Here, we report observation of a (239)Pu resonance from a solid sample of plutonium dioxide (PuO(2)) subjected to a wide scan of external magnetic field values (3 to 8 tesla) at a temperature of 4 kelvin. By mapping the external field dependence of the measured resonance frequency, we determined the nuclear gyromagnetic ratio (239)γ(n)(PuO(2))/2π to be 2.856 ± 0.001 megahertz per tesla (MHz/T). Assuming a free-ion value for the Pu(4+) hyperfine coupling constant, we estimated a bare (239)γ(n)/2π value of ~2.29 MHz/T, corresponding to a nuclear magnetic moment of μ(n) ≈ 0.15μ(N) (where μ(N) is the nuclear magneton).
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Affiliation(s)
- H Yasuoka
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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32
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Abstract
Magnetization, specific heat, and electrical resistivity measurements for polycrystalline specimens of CeRu(2)Ga(2)B reveal local moment ferromagnetic order at a Curie temperature T(C) = 16.3 K. Specific heat measurements show that the phase transition is second order and the low temperature behavior indicates that the Ce f-electron states do not hybridize strongly with the conduction electron states. Electrical resistivity measurements demonstrate large spin disorder scattering of conduction electrons for T ≥ T(C). Results for a single crystal are also reported, where T(C) = 15.4 K. While results for the polycrystal and single crystal specimens are qualitatively similar, the differences between them suggest that crystalline disorder plays a role in how the magnetism develops.
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Affiliation(s)
- R E Baumbach
- MPA-CMMS Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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33
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Das P, White JS, Holmes AT, Gerber S, Forgan EM, Bianchi AD, Kenzelmann M, Zolliker M, Gavilano JL, Bauer ED, Sarrao JL, Petrovic C, Eskildsen MR. Vortex lattice studies in CeCoIn5 with H is orthogonal to c. Phys Rev Lett 2012; 108:087002. [PMID: 22463558 DOI: 10.1103/physrevlett.108.087002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Indexed: 05/31/2023]
Abstract
We present small angle neutron scattering studies of the vortex lattice (VL) in CeCoIn5 with magnetic fields applied parallel (H) to the antinodal [100] and nodal [110] directions. For H is parallel to [100], a single VL orientation is observed, while a 90° reorientation transition is found for H is parallel to [110]. For both field orientations and VL configurations we find a distorted hexagonal VL with an anisotropy, Γ=2.0±0.05. The VL form factor shows strong Pauli paramagnetic effects similar to what have previously been reported for H is parallel to [001]. At high fields, above which the upper critical field (H(c2)) becomes a first-order transition, an increased disordering of the VL is observed.
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Affiliation(s)
- P Das
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
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34
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Park T, Lee H, Martin I, Lu X, Sidorov VA, Gofryk K, Ronning F, Bauer ED, Thompson JD. Textured superconducting phase in the heavy fermion CeRhIn5. Phys Rev Lett 2012; 108:077003. [PMID: 22401243 DOI: 10.1103/physrevlett.108.077003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Indexed: 05/31/2023]
Abstract
When antiferromagnetism and unconventional superconductivity coexist in CeRhIn(5) there is a significant temperature difference between resistively and thermodynamically determined transitions into the superconducting state. In this state, anisotropic transport near the superconducting transition reveals the emergence of textured superconducting planes that appear without a change in translational symmetry of the lattice. CeRhIn(5) is not unique in exhibiting these behaviors, indicating that textured superconductivity may be a general consequence of coexisting orders in correlated electron materials.
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Affiliation(s)
- Tuson Park
- Department of Physics, Sungkyunkwan University, Suwon, Korea
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35
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Altarawneh MM, Harrison N, Li G, Balicas L, Tobash PH, Ronning F, Bauer ED. Superconducting pairs with extreme uniaxial anisotropy in URu2Si2. Phys Rev Lett 2012; 108:066407. [PMID: 22401097 DOI: 10.1103/physrevlett.108.066407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Indexed: 05/31/2023]
Abstract
We report magnetic field orientation-dependent measurements of the superconducting upper critical field in high quality single crystals of URu(2)Si(2) and find the effective g factor estimated from the Pauli limit to agree remarkably well with that found in quantum oscillation experiments, both quantitatively and in the extreme anisotropy (≈10(3)) of the spin susceptibility. Rather than a strictly itinerant or purely local f-electron picture being applicable, the latter suggests the quasiparticles subject to pairing in URu(2)Si(2) to be "composite heavy fermions" formed from bound states between conduction electrons and local moments with a protected Ising behavior. Non-Kramers doublet local magnetic degrees of freedom suggested by the extreme anisotropy favor a local pairing mechanism.
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Affiliation(s)
- M M Altarawneh
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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36
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Bauer ED, Altarawneh MM, Tobash PH, Gofryk K, Ayala-Valenzuela OE, Mitchell JN, McDonald RD, Mielke CH, Ronning F, Griveau JC, Colineau E, Eloirdi R, Caciuffo R, Scott BL, Janka O, Kauzlarich SM, Thompson JD. Localized 5f electrons in superconducting PuCoIn₅: consequences for superconductivity in PuCoGa₅. J Phys Condens Matter 2012; 24:052206. [PMID: 22194040 DOI: 10.1088/0953-8984/24/5/052206] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The physical properties of the first In analog of the PuMGa(5) (M = Co, Rh) family of superconductors, PuCoIn(5), are reported. With its unit cell volume being 28% larger than that of PuCoGa(5), the characteristic spin-fluctuation energy scale of PuCoIn(5) is three to four times smaller than that of PuCoGa(5), which suggests that the Pu 5f electrons are in a more localized state relative to PuCoGa(5). This raises the possibility that the high superconducting transition temperature T(c) = 18.5 K of PuCoGa(5) stems from the proximity to a valence instability, while the superconductivity at T(c) = 2.5 K of PuCoIn(5) is mediated by antiferromagnetic spin fluctuations associated with a quantum critical point.
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Affiliation(s)
- E D Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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37
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Lu X, Lee H, Park T, Ronning F, Bauer ED, Thompson JD. Heat-capacity measurements of energy-gap nodes of the heavy-fermion superconductor CeIrIn5 deep inside the pressure-dependent dome structure of its superconducting phase diagram. Phys Rev Lett 2012; 108:027001. [PMID: 22324705 DOI: 10.1103/physrevlett.108.027001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Indexed: 05/31/2023]
Abstract
We use heat-capacity measurements as a function of field rotation to identify the nodal gap structure of CeIrIn(5) at pressures to 2.05 GPa, deep inside its superconducting dome. A fourfold oscillation in the heat capacity at 0.3 K is observed for all pressures, but with its sign reversed between 1.50 and 0.90 GPa. On the basis of recent theoretical models for the field-angle-dependent specific heat, all data, including the sign reversal, imply a d(x(2)-y(2)) order parameter with nodes along [110], which constrains theoretical models of the pairing mechanism in CeIrIn(5).
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Affiliation(s)
- Xin Lu
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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38
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Tobash PH, Ronning F, Thompson JD, Scott BL, Moll PJW, Batlogg B, Bauer ED. Single crystal study of the heavy-fermion antiferromagnet CePt₂In₇. J Phys Condens Matter 2012; 24:015601. [PMID: 22133582 DOI: 10.1088/0953-8984/24/1/015601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report the synthesis, structure, and physical properties of single crystals of CePt(2)In(7). Single crystal x-ray diffraction analysis confirms the tetragonal I4/mmm structure of CePt(2)In(7) with unit cell parameters a = 4.5886(6) Å, c = 21.530(6) Å and V = 453.32(14) Å(3). The magnetic susceptibility, heat capacity, Hall effect and electrical resistivity measurements are all consistent with CePt(2)In(7) undergoing an antiferromagnetic order transition at T(N) = 5.5 K, which is field independent up to 9 T. Above T(N), the Sommerfeld coefficient of specific heat is γ ≈ 300 mJ mol(-1) K(-2), which is characteristic of an enhanced effective mass of itinerant charge carriers. The electrical resistivity is typical of heavy-fermion behavior and gives a residual resistivity ρ(0) ∼ 0.2 µΩ cm, indicating good crystal quality. CePt(2)In(7) also shows moderate anisotropy of the physical properties that is comparable to structurally related CeMIn(5) (M = Co, Rh, Ir) heavy-fermion superconductors.
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Affiliation(s)
- Paul H Tobash
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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39
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Stock C, Sokolov DA, Bourges P, Tobash PH, Gofryk K, Ronning F, Bauer ED, Rule KC, Huxley AD. Anisotropic critical magnetic fluctuations in the ferromagnetic superconductor UCoGe. Phys Rev Lett 2011; 107:187202. [PMID: 22107668 DOI: 10.1103/physrevlett.107.187202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Indexed: 05/31/2023]
Abstract
We report neutron scattering measurements of critical magnetic excitations in the weakly ferromagnetic superconductor UCoGe. The strong non-Landau damping of the excitations we observe, although unusual, has been found in another related ferromagnet, UGe(2) at zero pressure. However, we also find that there is a significant anisotropy of the magnetic correlation length in UCoGe that contrasts with an almost isotropic length for UGe(2). The values of the magnetic correlation length and damping are found to be compatible with superconductivity on small Fermi-surface pockets. The anisotropy may be important to explain why UCoGe is a superconductor at zero pressure while UGe(2) is not.
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Affiliation(s)
- C Stock
- NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
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40
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Sakai H, Brown SE, Baek SH, Ronning F, Bauer ED, Thompson JD. Magnetic-field-induced enhancements of nuclear spin-lattice relaxation rates in the heavy-fermion superconductor CeCoIn5 using 59Co nuclear magnetic resonance. Phys Rev Lett 2011; 107:137001. [PMID: 22026890 DOI: 10.1103/physrevlett.107.137001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Indexed: 05/31/2023]
Abstract
(59)Co nuclear spin-lattice relaxation has been measured for the heavy-fermion superconductor CeCoIn(5) in a range of applied fields directed parallel to the c axis. An enhanced normal-state relaxation rate, observed at low temperatures and fields just above H(c2)(0), is taken as a direct measure of the dynamical susceptibility and provides microscopic evidence for an antiferromagnetic instability. The results are well described using the self-consistent renormalized theory for two-dimensional antiferromagnetic spin fluctuations, and parameters obtained in the analysis are applied to previously reported specific heat and thermal expansion data with good agreement.
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Affiliation(s)
- H Sakai
- Los Alamos National Laboratory, New Mexico 87545, USA.
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41
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Bauer ED, Yang YF, Capan C, Urbano RR, Miclea CF, Sakai H, Ronning F, Graf MJ, Balatsky AV, Movshovich R, Bianchi AD, Reyes AP, Kuhns PL, Thompson JD, Fisk Z. Electronic inhomogeneity in a Kondo lattice. Proc Natl Acad Sci U S A 2011; 108:6857-6861. [PMCID: PMC3084059 DOI: 10.1073/pnas.1103965108] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023] Open
Abstract
Inhomogeneous electronic states resulting from entangled spin, charge, and lattice degrees of freedom are hallmarks of strongly correlated electron materials; such behavior has been observed in many classes of d -electron materials, including the high-T c copper-oxide superconductors, manganites, and most recently the iron–pnictide superconductors. The complexity generated by competing phases in these materials constitutes a considerable theoretical challenge—one that still defies a complete description. Here, we report a manifestation of electronic inhomogeneity in a strongly correlated f -electron system, using CeCoIn5 as an example. A thermodynamic analysis of its superconductivity, combined with nuclear quadrupole resonance measurements, shows that nonmagnetic impurities (Y, La, Yb, Th, Hg, and Sn) locally suppress unconventional superconductivity, generating an inhomogeneous electronic “Swiss cheese” due to disrupted periodicity of the Kondo lattice. Our analysis may be generalized to include related systems, suggesting that electronic inhomogeneity should be considered broadly in Kondo lattice materials.
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Affiliation(s)
- E. D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Yi-feng Yang
- Los Alamos National Laboratory, Los Alamos, NM 87545
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - C. Capan
- Department of Physics and Astronomy, University of California, Irvine, CA 92697
| | - R. R. Urbano
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306
| | - C. F. Miclea
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - H. Sakai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan; and
| | - F. Ronning
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - M. J. Graf
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | | | - R. Movshovich
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - A. D. Bianchi
- Department de Physique, Universite de Montreal, Montreal, QC, Canada H3C 3J7
| | - A. P. Reyes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306
| | - P. L. Kuhns
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306
| | | | - Z. Fisk
- Department of Physics and Astronomy, University of California, Irvine, CA 92697
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42
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Altarawneh MM, Harrison N, Sebastian SE, Balicas L, Tobash PH, Thompson JD, Ronning F, Bauer ED. Sequential spin polarization of the Fermi surface pockets in URu2Si2 and its implications for the hidden order. Phys Rev Lett 2011; 106:146403. [PMID: 21561207 DOI: 10.1103/physrevlett.106.146403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Indexed: 05/30/2023]
Abstract
Using Shubnikov-de Haas oscillations measured in URu2Si2 over a broad range in a magnetic field of 11-45 T, we find a cascade of field-induced Fermi surface changes within the hidden order phase I and further signatures of oscillations within field-induced phases III and V [previously discovered by Kim et al., [Phys. Rev. Lett. 91, 256401 (2003)]. A comparison of kinetic and Zeeman energies indicates a pocket-by-pocket polarization of the Fermi surface leading up to the destruction of the hidden order phase I at ≈35 T. The anisotropy of the Zeeman energy driving the transitions in URu2Si2 points to an itinerant hidden order parameter involving quasiparticles whose spin degrees of freedom depart significantly from those of free electrons.
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Affiliation(s)
- M M Altarawneh
- Los Alamos National Laboratory, MS E536, Los Alamos, New Mexico 87545, USA
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43
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Lawrence JM, Wang CH, Christianson AD, Bauer ED. Heavy fermion scaling: uranium versus cerium and ytterbium compounds. J Phys Condens Matter 2011; 23:094210. [PMID: 21339563 DOI: 10.1088/0953-8984/23/9/094210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In an effort to explore the differences between rare-earth-based and uranium-based heavy fermion (HF) compounds that reflect the underlying difference between local 4f moments and itinerant 5f moments we analyze scaling laws that relate the low temperature neutron spectra of the primary ('Kondo-esque') spin fluctuation to the specific heat and susceptibility. While the scaling appears to work very well for the rare earth intermediate valence (IV) compounds, for a number of key uranium compounds the scaling laws fail badly. There are two main reasons for this failure. First, the presence of antiferromagnetic (AF) fluctuations, which contribute significantly to the specific heat, alters the scaling ratios. Second, the scaling laws require knowledge of the high temperature moment degeneracy, which is often undetermined for itinerant 5f electrons. By making plausible corrections for both effects, better scaling ratios are obtained for some uranium compounds. We point out that, while both the uranium HF compounds and the rare earth IV compounds have spin fluctuation characteristic energies of order 5-25 meV, they differ in that the AF fluctuations that are usually seen in the uranium compounds are never seen in the rare earth IV compounds. This suggests that the 5f itineracy increases the f-f exchange relative to the rare earth case.
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Park T, Sidorov VA, Lee H, Ronning F, Bauer ED, Sarrao JL, Thompson JD. Unconventional quantum criticality in the pressure-induced heavy-fermion superconductor CeRhIn₅. J Phys Condens Matter 2011; 23:094218. [PMID: 21339571 DOI: 10.1088/0953-8984/23/9/094218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The lack of superconductivity in several candidate materials that exhibit a non-spin density wave quantum critical point has raised the question of whether the associated spectra of quantum fluctuations are beneficial to forming superconducting electron pairs. Here we discuss the possibility that the prototypical heavy-fermion antiferromagnet CeRhIn5 may be the first example of unconventional superconductors where superconductivity arises from Kondo-breakdown quantum criticality.
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Affiliation(s)
- Tuson Park
- Department of Physics, Sungkyunkwan University, Suwon 440-746, Korea. Los Alamos National Laboratory, Los Alamos, NM 87544, USA
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45
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Bauer ED, Tobash PH, Mitchell JN, Kennison JA, Ronning F, Scott BL, Thompson JD. Magnetic order in Pu₂M₃Si₅ (M = Co, Ni). J Phys Condens Matter 2011; 23:094223. [PMID: 21339576 DOI: 10.1088/0953-8984/23/9/094223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of two new plutonium compounds Pu2M3Si5 (M = Co, Ni) are reported. Pu2Ni3Si5 crystallizes in the orthorhombic U2Co3Si5 structure type, which can be considered a variant of the BaAl4 tetragonal structure, while Pu2Co3Si5 adopts the closely related monoclinic Lu2Co3Si5 type. Magnetic order is observed in both compounds, with Pu2Ni3Si5 ordering ferromagnetically at T(C) = 65 K then undergoing a transition into an antiferromagnetic state below T(N) = 35 K. Two successive magnetic transitions are also observed at T(mag1) = 38 K and T(mag2) = 5 K in Pu2Co3Si5. Specific heat measurements reveal that these two materials have a moderately enhanced Sommerfeld coefficient γ ∼ 100 mJ/mol Pu K(2) in the magnetic state with comparable RKKY and Kondo energy scales.
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Affiliation(s)
- E D Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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46
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Tobash PH, Jiang Y, Ronning F, Booth CH, Thompson JD, Scott BL, Bauer ED. Synthesis, structure and physical properties of YbNi3Al9.23. J Phys Condens Matter 2011; 23:086002. [PMID: 21411905 DOI: 10.1088/0953-8984/23/8/086002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The physical properties of YbNi(3)Al(9.23(1)), including the crystal structure, magnetization, specific heat, valence, and electrical resistivity, are reported. Single crystal x-ray diffraction reveals that the compound crystallizes with the rhombohedral space group R32 and has unit cell parameters a = 7.2443(3) Å and c = 27.251(3) Å with some crystallographic disorder at Al sites. The compound orders antiferromagnetically at T(N) = 3 K despite the presence of strong ferromagnetic correlations, accompanied by a spin-flop-like transition to a moment-aligned state above 0.1 T. X-ray absorption spectroscopy and magnetic susceptibility measurements indicate a localized Yb(3+) electronic configuration, while the Sommerfeld coefficient for the magnetically ordered state was determined as approximately 135 mJ mol(-1) K(-2), suggesting moderately heavy fermion behavior. Therefore, these data indicate a balance between competing Ruderman-Kittel-Kasuya-Yosida (RKKY) and Kondo interactions in YbNi(3)Al(9.23(1)) with a somewhat dominant RKKY interaction that leads to a relatively high ordering temperature.
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Affiliation(s)
- P H Tobash
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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47
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Zaum S, Grube K, Schäfer R, Bauer ED, Thompson JD, v Löhneysen H. Towards the identification of a quantum critical line in the (p, B) phase diagram of CeCoIn5 with thermal-expansion measurements. Phys Rev Lett 2011; 106:087003. [PMID: 21405592 DOI: 10.1103/physrevlett.106.087003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Indexed: 05/30/2023]
Abstract
The low-temperature thermal expansion of CeCoIn(5) single crystals measured parallel and perpendicular to magnetic fields B oriented along the c axis yields the volume thermal-expansion coefficient β. Considerable deviations of β(T) from Fermi-liquid behavior occur already within the superconducting region of the (B, T) phase diagram and become maximal at the upper critical field B(c2)(0). However, β(T) and the Grüneisen parameter Γ are incompatible with a quantum critical point at B(c2)(0), but allow for a quantum criticality shielded by superconductivity and extending to negative pressures for B<B(c2)(0). We construct a tentative (p, B, T) phase diagram of CeCoIn(5) suggesting a quantum critical line in the (p, B) plane.
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Affiliation(s)
- S Zaum
- Institut für Festkörperphysik, Karlsruhe Institute of Technology, D-76021 Karlsruhe, Germany
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48
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Gofryk K, Sefat AS, McGuire MA, Sales BC, Mandrus D, Imai T, Thompson JD, Bauer ED, Ronning F. Effect of annealing on the specific heat of optimally doped Ba(Fe0.92Co0.08)2As2. ACTA ACUST UNITED AC 2011. [DOI: 10.1088/1742-6596/273/1/012094] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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49
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Kothapalli K, Ronning F, Bauer ED, Schultz AJ, Nakotte H. Single-crystal neutron diffraction studies on Ni-based metal-pnictide superconductor BaNi2As2. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/251/1/012010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Baek SH, Sakai H, Bauer ED, Mitchell JN, Kennison JA, Ronning F, Thompson JD. Anisotropic spin fluctuations and superconductivity in "115" heavy fermion compounds: ⁵⁹Co NMR study in PuCoGa₅. Phys Rev Lett 2010; 105:217002. [PMID: 21231343 DOI: 10.1103/physrevlett.105.217002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 10/03/2010] [Indexed: 05/30/2023]
Abstract
We report results of ⁵⁹Co nuclear magnetic resonance measurements on a single crystal of superconducting PuCoGa₅ in its normal state. The nuclear spin-lattice relaxation rates and the Knight shifts as a function of temperature reveal an anisotropy of spin fluctuations with finite wave vector q. By comparison with the isostructural members, we conclude that antiferromagnetic XY-type anisotropy of spin fluctuations plays an important role in mediating superconductivity in these heavy fermion materials.
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Affiliation(s)
- S-H Baek
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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